Photodegradable polyesters

ABSTRACT

This invention relates to a polyester comprising repeating units having the structure: ##STR1## wherein R 1  is selected from the group consisting of hydrogen, alkyl having 1 to 6 carbon atoms and aryl having 6 to 10 carbon atoms and R 2  is selected from the group consisting of hydrogen, alkyl having 1 to 6 carbon atoms, and aryl having 6 to 10 carbon atoms.

FIELD OF THE INVENTION

This invention relates to the ketone,1,5-bis-(4'-alkoxycarbonylphenyl)-3-pentanone, which renders polyestersphotodegradable when it is included to form a copolymer.

BACKGROUND OF THE INVENTION

Polyesters, particularly those used for food and beverage packaging,have some very desirable features, such as safety and low cost oftransportation. However, when these containers are not recycled or areimproperly discarded, they represent an aesthetic blight on thelandscape. Therefore, it would be very desirable to develop a polyesterthat retains the useful properties of these polyester packages but woulddissipate spontaneously in the environment when discarded improperly.

One approach to this problem would be to take advantage of thedegradative effect of the strong ultraviolet radiation emitted naturallyby the sun. It is already known in the art that the introduction of someketone-containing moieties into a polyester chain gives an ultravioletsensitivity to polyesters, causing them to become brittle in theprocess. The brittleness causes the polyesters to crumble and ultimatelydissipate.

Reportedly, the degradation requires shorter wavelength ultravioletradiation, generally in the range of 280-320 nanometers. Thesewavelengths are generally filtered out of the spectrum by ordinaryglass. Therefore, since the requisite ultraviolet wavelengths are notpresent in indoor environments, the rate of degradation indoors would bevery slow.

We have discovered ketones which introduce ultraviolet sensitivity to apolyester.

U.S. Pat. No. 4,965,399 discloses 1,5-bis(substituted-aryl)-3-pentanolswhich are useful in the preparation of polymeric materials.

U.S. Pat. No. 5,025,086 discloses1,5-bis(4-carboxycyclohexyl)-3-pentanol and its esters and processes fortheir preparation.

U.S. Pat. No. 3,878,169 discloses polyesters which contain ketone groupsin the side chains, but not in the backbone of the polyester.

It has heretofore been unknown to use ketones such as those used in thisinvention as a repeating unit in the structure of a polyester.

SUMMARY OF THE INVENTION

This invention relates to a polyester comprising repeating units of:##STR2## wherein R¹ is selected from the group consisting of hydrogen,alkyl having 1 to 6 carbon atoms and aryl having 6 to 10 carbon atomsand R² is selected from the group consisting of hydrogen, alkyl having 1to 6 carbon atoms and aryl having 6 to 10 carbon atoms.

This ketone introduces ultraviolet sensitivity to a polyester which thepolyester previously did not possess at the same level.

An additional advantage of this ketone is, since the levels required toimpart the desirable photosensitivity are relatively low, theintroduction of this material should not significantly effect the normalprocessing of these polymers. The ketone has the added advantage ofbeing derived from methyl 4-formyl benzoate, an inexpensive and readilyavailable by-product of dimethyl terephthalate production which mustotherwise be recycled or disposed in an environmentally sound fashion.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

This invention relates to substituted 3-pentanones, such as1,5-bis-(4,'-alkoxycarbonylphenyl)-3-pentanone. The ketone,1,5-bis-(4,-methoxycarbonylphenyl)-3-pentanone, is a more specificexample of this type of ketone.

Specifically, this invention relates to a polyester comprising repeatingunits of: ##STR3## wherein R¹ is selected from the group consisting ofhydrogen, alkyl having 1 to 6 carbon atoms and aryl having 6 to 10carbon atoms and R² is selected from the group consisting of hydrogen,alkyl having 1 to 6 carbon atoms and aryl having 6 to 10 carbon atoms.

For the purposes of this invention, examples of alkyl having 1 to 6carbon atoms are methyl, ethyl, propyl, butyl, pentyl, isobutyl,isopropyl and hexyl. Examples of aryl having 6 to 10 carbon atoms arephenyl, naphthyl and xylyl. It is preferred that R¹ and R² both areeither hydrogen, methyl or phenyl. It is more preferred that R¹ and R²are hydrogen.

It is preferred that the repeating unit which is a ketone is present inthe polyester in an amount of 0.1-100 mole percent, preferably 0.1-15mole percent, and more preferably 1.0-5 mole percent of the repeatingunits derived from diacids and diesters.

As an example of the process for making the substituted 3-pentanones, aspecific example is provided hereafter:

1,5-bis-(4'-methoxycarbonylphenyl)-3-pentanone is synthesized in thefollowing manner:

Methyl 4-formyl benzoate was condensed with acetone to generate1,5-bis-(4'-methoxycarbonylphenyl)-1,4-pentadien-3-one and subsequentlyhydrogenated over an hydrogenation catalyst. The following schematicrepresents these reactions: ##STR4## The biscondensation ofbenzaldehydes with ketones, particularly acetone, is a well knownprocess as disclosed by R. Conrad and M. A. Dolliver, Org. Syn., Coll.Vol. II, 167 (1943). The condensation shown is base catalyzed.

The invention also relates to a process for the preparation of apolyester comprising repeating unit (A) and comprising less than 0.5mole % repeating unit (B) based on the total number of moles of diacidsor diesters, wherein ##STR5## wherein R¹ is selected from the groupconsisting of hydrogen, alkyl having 1 to 6 carbon atoms or aryl having6 to 10 carbon atoms and R² is selected from the group consisting ofhydrogen, alkyl having 1 to 6 carbon atoms, or aryl having 6 to 10carbon atoms which comprises the steps of:

(1) reacting a 4-substituted-benzaldehyde(s) having the formula:##STR6## with a ketone having the formula: ##STR7## in the presence ofan acidic or basic condensation catalyst to obtain an intermediatecompound having the formula: ##STR8##

(2) hydrogenating the intermediate compound in the presence of acatalytic amount of a hydrogenation catalyst selected from mixedcopper-chromium oxides and supported Group VIII nobel metals underhydrogenation conditions of pressure and temperature; wherein thestructure ##STR9## R¹ is selected from the group consisting of hydrogen,alkyl having 1 to 6 carbon atoms and aryl having 6 to 10 carbon atomsand R² is selected from the group consisting of hydrogen, alkyl having 1to 6 carbon atoms, and aryl having 6 to 10 carbon atoms, and R³ and R⁴are selected from the group consisting of hydrogen and alkyl having 1 to6 carbon atoms. R³ and R⁴ are preferably alkyl having 1 to 2 carbons;

(3) polymerization of the diester with other diesters or diacids anddiol or diols at temperatures of 200°-300° C. and pressures of 1000 mmto 0.01 mm.

The first step of the above-described process is carried out by reactingapproximately 2 moles of the aldehyde per mole of ketone in the presenceof an acidic or basic catalyst.

Examples of materials which may be used as the catalyst include thealkali metal hydroxides, alkoxides and carbonates; the alkaline earthhydroxides and oxides; quaternary ammonium hydroxides such astetra-unsubstituted or substituted alkylammonium hydroxides wherein thefour alkyl residues contain a total of up to about 20 carbon atoms;alkyl- and aryl-sulfonic acids; acidic ion exchange resins such asAmberlyst 15; and mineral acids such as sulfuric and hydrochloric acid.

The condensation reaction normally is conducted in the presence of aninert solvent such as aliphatic and aromatic hydrocarbons, e.g., havingfrom about 6 to 12 carbon atoms and alkanols, .e.g., having up to about6 carbon atoms.

Methanol is the preferred solvent since it is compatible with methylesters and generally dissolves all of the reaction components. Thetemperature of the condensation step can be varied substantiallydepending on a number of factors such as the reactants and catalystbeing used, catalyst concentration, etc. Although temperatures as low as-25° C. and as high as 250° C. may be used under some circumstances, thecondensation reaction normally will be performed at a temperature in therange of about 0° to 140° C., preferably 0° to 50° C.

Pressure is not normally important for the condensation and, whilepressure moderately above or below atmospheric may be used, the firststep most conveniently is done at ambient pressure.

Examples of the Group VIII noble metals which may be used to catalyzethe hydrogenation, the second step, include palladium and platinum. Aparticularly preferred catalyst is palladium. Examples of the materialson which the Group VIII noble metals may be supported include silica,alumina, alumina silica, carbon, titania, etc.

The concentration of the Group VIII metal catalyst can varysubstantially depending on a number of factors such as the activityand/or selectivity of the particular catalyst, the surface area of thecatalyst, the hydrogenation conditions, the mode of operation, etc. Forexample, when using a tricklebed hydrogenation system wherein a solutionof a 1,5-bis(4'-substituted aryl)penta-1,4-dien-3-one flows over andthrough one or more fixed beds of the catalyst in granular form in ahydrogen atmosphere at elevated temperature and pressure, theconcentration of the catalyst relative to the reactant cannot bedetermined with any degree of accuracy.

The hydrogenation conditions of temperature and pressure may vary over awide range depending, for example, on the factors referred to aboveconcerning catalyst concentration. Furthermore, to some extent,temperature and pressure are interdependent and, thus, increasing onemay permit lowering of the other. Generally, the hydrogenationconditions will be within the ranges of about 20° to 300° C. and about10 to 500 psig hydrogen. The preferred ranges are about 20° to 200° C.and about 15 to 250 psig hydrogen. Typically, the hydrogenation iscarried out in the presence of an inert organic solvent for the1,5-bis(4'-substituted-aryl) penta-1,4-dien-3-one.

Examples of solvents which may be used include hydrocarbons such asaliphatic, cycloaliphatic and aromatic hydrocarbons containing about 6to 12 carbon atoms, e.g., benzene, toluene, xylene, cumene,psuedocumene, diisopropylbenzene, cyclohexane, hexane, heptane, etc.;carboxylic acid esters such as alkyl carboxylates containing up to about6 carbon atoms, e.g., methyl acetate, ethyl acetate, methyl butyrate,etc; alkanols containing up to about 6 carbon atoms, e.g., methanol,ethanol, 2-propanol, etc. The concentration of the pentadienone reactantin the solvent is not important and is limited only by the solubility ofthe particular reactant in the solvent being used and economicconsiderations. For most reactants the preferred inert organic solventsare toluene, xylene, 2-propanol and methanol.

It is generally accepted that olefin hydrogenation is a simple processin most instances. We have found, however, that the hydrogenation of1,5-bis-(4'-alkoxycarbonylphenyl)-1,4-pentadien-3-one to 1,5-bis(4'-alkoxycarbonylphenyl)-3-pentanone was less than trivial. Often,1,5-bis-(4'-alkoxycarbonylphenyl)-3-pentanol is obtained as aby-product. The loss of selectivity upon attempting to hydrogenateunsaturated ketones has been previously observed but has seriousconsequences in this invention.

Whereas 1,5-bis-(4'-carbomethoxyphenyl)-3-pentanone and1,5-bis-(4'-carbomethoxyphenyl)-3-pentanol are separable by severalacceptable laboratory techniques, such as chromatography, methods moreamenable to industrial level preparations, particularly crystallization,result in substantial losses of the desired ketone.

Typically, 1,5-bis-(4'-alkoxycarbonylphenyl)-3pentanone and1,5-bis-(4'-alkoxycarbonylphenyl)-3-pentanol co-crystalize in a ratio ofapproximately 3:1 when significant amounts of1,5-bis-(4'-alkoxycarbonylphenyl)-3-pentanol are present.

Further complicating the process is the observation that even smallquantities of 1,5-bis-(4'-alkoxy-carbonylphenyl)-3-pentanol have seriousconsequences in the subsequent polymerization. Since1,5-bis-(4'-alkoxycarbonylphenyl)-3-pentanol is trifunctional withrespect to polyester formation, it acts to branch and crosslinkpolyesters resulting in unacceptable product properties when present ingreater than about 0.5 mole % based on the total number of moles ofdiacid or diester.

Unless substantial yield losses and a difficult operation are to betolerated, this requires one of two approaches to attaining the pure1,5-bis-(4'-alkoxycarbonylphenyl)-3-pentanone required from thisprocess. Either the hydrogenation of1,5-bis-(4'-alkoxycarbonylphenyl)-1,4-pentadien-3-one to1,5-bis(4'-alkoxycarbonylphenyl)-3-pentanone must proceed with very highselectivity, which represents the preferred process, or the by-product1,5-bis-(4'-alkoxycarbonyl)3-pentanol must be reoxidized to1,5-bis-(4'-alkoxycarbonylphenyl)-3-pentanone. We have demonstrated thateither approach is viable.

The key to making the preferred approach operate is the judicious choiceof catalyst. This is much more difficult than it would appear. Althoughit would be anticipated that almost all hydrogenation catalysts wouldyield the desired 1,5-bis-(4'-alkoxycarbonylphenyl)-3-pentanone,identifying catalysts with the appropriate high selectivity to thedesired product required extensive effort. We have found at least twocatalyst combinations that may be effective for the desiredtransformation in nearly 100% selectivity. These were 5% palladium oncarbon operated at slightly elevated temperatures and atmosphericpressure and a quinoline-poisoned 0.5% platinum on alumina whichoperated at elevated temperature and pressure.

A large variety of solvents are useful as the reaction medium, althoughthe most preferred would be lower molecular weight alcohols, esters,ketones, carboxylic acids, or aromatic hydrocarbons since the startingmaterials are soluble to some appreciable degree in these solvents,particularly at elevated temperatures.

Specifying a temperature and pressure for this part of the process wouldprove difficult since it would be very dependent upon the choice ofcatalyst and solvent. For example, a poisoned platinum catalyst operatedat 175° C. and 250 psig in toluene might operate similar to a palladiumcatalyst on carbon operated at 50° C. and 15-30 psi.

However, successful processes, defined as having a high selectivity tothe desired 1,5-bis-(4'-alkoxy-carbonylphenyl)-3-pentanone, would beexpected to generally proceed at lower temperatures and pressures thanthe processes which give substantial amounts of undesired alcohol.

Processes in which 1,5-bis-(4'-alkoxycarbonyl-phenyl)-3-pentanol isobtained as a co-product may also be used with an added oxidationprotocol, although it is obviously not the preferred approach since itadds a step to the overall process. Methods of oxidizing alcohols arenumerous, well known to any practitioner of the art, and can be found inany good text on organic chemistry. Suitable reagents include sodiumhypochlorite in acetic acid and chromic acid in aqueous sulfuric acid.

To exemplify this reoxidation approach, we utilized an Oppenhaueroxidation which entailed treating a mixture of1,5-bis-(4'-methoxycarbonylphenyl)-3-pentanol and1,5-bis-(4'-methoxycarbonylphenyl)-3-pentanone with cyclohexanone in thepresence of a catalytic quantity of aluminum isopropoxide in refluxingtoluene.

This treatment converted a mixture of ca. 1:11,5-bis-(4'-methoxycarbonylphenyl)-3-pentanol to1,5-bis(4'-methoxycarbonylphenyl)-3-pentanone to a mixture which waswell in excess of 90% the desired1,5-bis-(4'-methoxycarbonyl)-3-pentanone.

The copolymerization of 1,5-bis-(4'-methoxy-carbonylphenyl)-3-Pentanoneoccurs using conditions which are similar to those used in commercialproduction of polyesters. Initially,1,5-bis-(methoxycarbonyl-phenyl)-3-pentanone is included in minoramounts (<5 mol % based on the total amount of diesters) in acopolymerization reaction with an acid and glycol under relatively mildconditions. These reaction conditions give a polymer that has propertiessimilar to those of unmodified poly(ethylene terephthalate) which hasbeen prepared under the same conditions.

The glycol useful in the invention comprises a diol selected from thegroup consisting of ethylene glycol; 1,2-propanediol; 1,3-propanediol;2,4-dimethyl-2-ethylhexane-1,3-diol; 2,2-dimethyl-1,3-propanediol;2-ethyl-2-butyl-1,3-propanediol; 2-ethyl-2-isobutyl-1,3propanediol;1,3-butanediol; 1,4-butanediol; 1,5-pentanediol, 1,6-hexanediol,2,2,4-trimethyl-1,3-pentanediol; thiodiethanol;1,2-cyclohexanedimethanol; 1,3-cyclohexanedimethanol;1,4-cyclohexanedimethanol; 2,2,4,4-tetramethyl-1,3-cyclobutanediol;p-xylylenediol; diethylene glycol, triethylene glycol; tetraethyleneglycol; and pentaethylene, hexaethylene, heptaethylene, octaethylene,nonaethylene, and decaethylene glycols or combinations thereof.

The polyester of the invention further comprises a dicarboxylic acidresidue selected from the group consisting of oxalic; malonic;dimethylmalonic; succinic; glutaric; adipic; trimethyladipic; pimelic;2,2-dimethylglutaric; azelaic; sebacic; fumaric; maleic; itaconic;1,3-cyclopentanedicarboxylic; 1,2-cyclohexanedicarboxylic;1,3-cyclohexanedicarboxylic; 1,4-cyclohexanedicarboxylic; phthalic;terephthalic; isophthalic; 2,5-norbornanedicarboxylic; 1,4-naphthalic;diphenic; 4,4'-oxydibenzoic; diglycolic; thiodipropionic;4,4'-sulfonyldibenzoic; 4,4'-biphenyldicarboxylic; and2,6-naphthalenedicarboxylic acids or esters thereof and combinationsthereof.

The polyesters of the invention are useful in preparing sheets, films,fibers and molded objects.

It was later discovered that harsher conditions (higher temperatures andother catalyst systems) also produced high quality copolymers in evenhigher molecular weight (Inherent viscosity=0.60). The1,5-bis-(4'-methoxycarbonylphenyl)-3-pentanone was later successfullycopolymerized at much higher levels than 5%. The success of thesereactions is generally dependent on the purity of the1,5-bis-(4'-methoxycarbonylphenyl)-3-pentanone. When material of highpurity is used, an essentially linear polyester is produced. Thepresence of 1,5-bis-(4'-methoxycarbonyl phenyl)-3-pentanone in thecopolyesters had no detrimental effect on solid stating. Therefore, themolecular weights of the copolyesters can, if desired, be increasedbeyond what is possible in the melt phase.

The 1,5-bis-(4'-methoxycarbonylphenyl)-3-pentanone was copolymerizedwith monomers in addition to dimethyl terephthalate and ethylene glycol,such as 1,4-bis(hydroxymethyl) cyclohexane and diethylene glycol.

The photodegradation of copolyesters prepared from1,5-bis-(4'-methoxycarbonylphenyl)-3-pentanone will be discussed asfollows:

Polyethylene has been made photodegradable by incorporation of ketonecarbonyl groups into the polymer backbone at low levels (0.1-5%) asdisclosed by G. M. Harlan and A. Nicholas, Proceedings of Symposium onDegradable Plastics, The Society of the Plastics Industry, Inc.,Washington, D.C., Jun. 10, 1987, p. 14, and by J. E. Potts, "Plastics,Environmentally Degradable," for the Encyclopedia of ChemicalTechnology, John Wiley and Sons, Section C-5, Oct. 13, 1982.

Commercial processes for the production of ethylene-carbon monoxide(ECO) copolymer are in place. This material is commercially available.These photodegradable materials are being used already in applicationswhere photodegradability is desired, such as 6-ring binders and garbagebags. These polymers are photodegradable because the ultravioletradiation in sunlight causes cleavage of the polymer chains near theketone groups.

In this invention, copolyesters prepared from low levels (0.5-10 mol %)of 1,5-bis-(4'-methoxycarbonylphenyl)-3-pentanone are shown to bephotodegradable also. Upon exposure to ultraviolet radiation, thecopolyesters prepared from1,5-bis-(4'-methoxycarbonylphenyl)-3-pentanone did not lose theirstructural integrity as fast as similar ECO copolymers did. Amorphousfilms prepared from these copolyesters did photodegrade (lose theirstructural integrity) both in a Weather-Ometer (AATCC-16-E) and insunlight. The conditions in the Weather-Ometer (AATCC-16-E) were asfollows: Xenon arc lamp, 63° C. and 30% relative humidity. The filmswere mounted so that the light shone directly on one side of the film asit orbited around the light. The degradation was evidenced by thebrittleness observed when the irradiated films were creased and by thelarge increases in the molecular weight distribution (quotient of theZ-average molecular weight and the number-average molecular weight). Themolecular weight distribution for unmodified poly(ethylene)terephthalatedoes not increase upon irradiation for 400 hours in the Weather-Ometer.About three months (February through April) of exposure to sunlight inTennessee was equivalent to approximately 400 hours exposure in a xenonarc Weather-Ometer at 63° C. and 30% relative humidity.

Later experiments were conducted on oriented films. The polyesters ofthis invention can be oriented in one or both directions by stretchingfilms at temperatures above the glass transition temperature of thepolyester. Optimum orientation temperatures are 10° to 40° C. above theglass transition temperatures. These oriented films also degraded whenexposed to ultraviolet radiation, as evidenced by decreases inelongation and tensile strength. This is important since many articlesprepared from polyesters are oriented during the fabrication process.

This invention can be further illustrated by the following examples ofpreferred embodiments thereof, although it will be understood that theseexamples are included merely for purposes of illustration and are notintended to limit the scope of the invention unless otherwisespecifically indicated. The starting materials are commerciallyavailable unless otherwise noted. All percentages are by weight unlessotherwise indicated.

Abbreviations

mL=milliliter; L=liter; g=gram; hr=hour; s=singlet; d=doublet; Hz=hertz;MHz=megahertz; HNMR=Nuclear Magnetic Resonance Spectroscopy forhydrogen; IR=infrared spectroscopy; psi--pounds per square inch;mm=millimeters; ppm=parts per million; mPa=megapascal.

EXAMPLES Example 1

Condensation of Methyl 4-Formyl Benzoate With Acetone

This procedure describes a typical base catalyzed condensation of methyl4-formyl benzoate with acetone and is the procedure generally used.

A solution of 0.55 moles (90.3 g) of methyl 4-formyl benzoate wasprepared under an inert atmosphere using a mechanical stirrer. (Theinert atmosphere is maintained throughout the reaction to minimizeoxidation of the methyl 4-formyl benzoate.) To this solution was added0.25 (14.5 g, 18.3 mL) moles of acetone. A cooling bath, consistingsimply of an evaporating dish filled with cold tap water, was placedunder the reaction vessel and a solution of 2.5 g (0.0625.moles) of NaOHin 25 mL of 1:1 methanol/water was added slowly using an additionfunnel. The rate of addition is determined by the temperature of thereaction which is maintained at less than 35° C.

When the reaction began, the solution initially turned yellow and then alight yellow precipitate formed which eventually became a thick slurry.

After 2.5 hrs. the reaction mixture was filtered and washed withmethanol until the wash solution is no longer dark. The product wasallowed to air dry on the filter to yield 82.9 g (95% yield) of1,5-bis-(4'-methoxy-carbonylphenyl)-1,4-pentadien-3-one.

The product could be readily recrystallized from acetic acid or xylene.HNMR (CDCl₃) 270 MHz δ=3.93 (s,6H), 7.15(d,2H, J=16 Hz), 7.68 (d,4H,J=10 Hz), 7.76 (d,2H, J=16 Hz), 8.09 (d,4H, J=10Hz). IR (KBr): 1720,1653, 1284 cm.sup.⁻¹. Elemental Analysis: Calc. for C₂₁ H₁₂ O₅ :C,71.99; H,5.18. Found: C,71.98; H,5.15. m.p. 221°-223° C.

Example 2 Synthesis of 1,5-Bis-(4'-Methoxycarbonylphenyl)-3-Pentanone

A heterogeneous mixture of 71.7 g of1,5-bis-(4'-methoxycarbonyl-phenyl)-1,4-pentadien-3-one, 3.8 grams of 5%Pd on carbon, and 650 mL of 2-propanol was prepared in a 1 L 3-neckedflask. The mixture was stirred mechanically and heated to 50° C. Thesystem was flushed with hydrogen, and hydrogen was then supplied on acontinuous basis at about 20 psi. The hydrogen uptake was initially veryrapid, but gradually slowed. When hydrogen uptake nearly ceased, thehydrogen source was removed. The vessel was heated to 75°-80° C. andpurged thoroughly with nitrogen. The hot product was filtered through asteam-jacketed Buchner funnel which contained a pad of filter-aid. Thehot filtrate immediately began to precipitate the product.

The filtrate was allowed to cool to room temperature and was then placedin a freezer at -15° C. to complete the precipitation of the product.The product was filtered and dried to yield 58.21 grams (80% yield) of1,5-bis-(methoxycarbonylphenyl)-3-pentanone. Reduction in the volume toca. 200 mL and cooling yielded an additional 1.59 grams of productgiving a total yield of 82%. HNMR (CDCl₃) 270 MHz δ=2.72 (t,4H), 2.93(t,4H), 3.91 (s,6H), 7.21 (d,4H), 7.94 (d,2H). FDMS (M+/e): 3.54.Elemental Analysis: Calc. for C₂₁ H₁₆ O₅ : C,71.17; H,6.26. Found:C,71.27; H,6.33. m.p. 105°-108° C.

Example 3

This example demonstrates that another catalyst is useful. Aheterogeneous mixture of 10.0 g of1,5-bis(4'-methoxycarbonylphenyl)-1,4-pentadien-3-one, 1.0 gram of 0.5%Pt on alumina catalyst, 0.2 mL of quinoline, and 100 mL of toluene wasprepared in an hydrogenation autoclave. The autoclave was pressurized to25 psi with hydrogen and then heated to 175° C. Upon reaching thedesired temperature, the pressure was adjusted to 250 psi with hydrogen.These conditions were maintained for 5 hours, and the reaction wasallowed to cool to room temperature. The product was filtered, and thesolid product was determined to be pure1,5-bis-(4'-methoxycarbonylphenyl)-3-pentanone by gas chromatographicanalysis.

Example 4

This example demonstrates a case in which the desired1,5-bis-(methoxycarbonylphenyl)-3-pentanone is obtained as a mixturewith the undesired, overhydrogenation product,1,5-bis-(4'-methoxycarbonylphenyl)-3-pentanol. A heterogeneous mixtureof 10.0 g of 1,5-bis(4'-methoxycarbonylphenyl)-1,4-pentadien-3-one, 1.0grams of 5% rhodium on carbon catalyst, and 100 mL cyclohexane wasprepared in an hydrogenation autoclave. The autoclave was pressurized to25 psi with hydrogen and then heated to 175° C. Upon reaching thedesired temperature the pressure was adjusted to 250 psi with hydrogen.These conditions were maintained for 5 hrs, and the reaction was allowedto cool to room temperature. The product was filtered, and the solidproduct composition determined to be 75%1,5-bis-(4'-methoxycarbonylphenyl)-3-pentanone and 19%1,5-bis-(4'-methoxycarbonylphenyl)-3-pentanol by gas chromatographicanalysis.

Example 5

This example demonstrates one example of an oxidative protocol forconverting mixtures of the desired1,5-bis-(4'-methoxycarbonylphenyl)-3-pentanone and undesired,overhydrogenation product, 1,5-bis-(methoxycarbonylphenyl)-3-pentanol,which are often obtained in the hydrogenation, to mixtures enriched inthe desired 1,5-bis-(methoxy-carbonylphenyl)-3-pentanone. A solution of2.0 grams aluminum isopropoxide in 100 mL of toluene was prepared andfiltered to remove any residual insoluble material. To this solution wasadded 20 grams of a 1:1 mixture of1,5-bis-(4'-methoxycarbonylphenyl)-3-pentanone and1,5-bis-(4'-methoxycarbonylphenyl)-3-pentanol and 25 mL ofcyclohexanone. The reaction was heated at reflux overnight. The mixturewas analyzed by gas chromatographic analysis and determined to contain93% 1,5-bis-(methoxycarbonylphenyl)-3-pentanone and 7%1,5-bis-(methoxycarbonylphenyl)-3-pentanol.

Example 6 Copolymerization of1,5-bis-(methoxycarbonylphenyl)-3-pentanone, Dimethyl terephthalate andethylene glycol

Dimethyl terephthalate (0.475 mol, 92.2 g),1,5-bis-(4'-methoxycarbonylphenyl)-3-pentanone (0.025 mol, 8.85 g),ethylene glycol (1.00 mol, 62 g), manganese diacetate (55 ppm ofmanganese), cobalt diacetate (80 ppm of cobalt), and antimony trioxide(220 ppm of antimony) were combined in a flask and stirred undernitrogen at 200° C. for 1 h, 210° C. for 1.25 h, and 220° C. for 1 h.During this period of time the theoretical amount of methanol distilledfrom the reaction. The temperature was then increased to 270° C. After10 min a vacuum was slowly applied. The temperature was maintained at270° C. for 1.67 h at a vacuum of 0.05 mm of Hg. A light greencrystalline polymer resulted. Inherent viscosity=0.60 [0.5 wt % solutionin phenol/tetrachloroethane (60:40)]. Nuclear magnetic resonancespectroscopy indicates that the polyester contains 5 mol % of therepeating unit from the ketone-containing monomer. Tg=76.0° C.; Tm=245°C.

Example 7

Solid Stating of Copolyester from Example 1

Particles (approximately 3 mm) of the copolyester described in Example 6were heated to 207° C. and continuously flushed with nitrogen for 8hours. The inherent viscosity increased from 0.60 to 0.88, indicating asignificant increase in molecular weight. Gel permeation chromatographyshowed that the copolyester remained essentially linear during thisprocess.

Example 8

Weathering of Amorphous Films of the Copolyesters

Amorphous films (150-200 microns) of the poly(ethylene)terephthalatemodified with low levels of1,5-bis-(4'-methoxycarbonylphenyl)-3-pentanone were prepared andweathered for 400 hours in a xenon arc Weather-Ometer (AATCC-16-E). Thetable below shows the changes in the quotient of the Z-average molecularweight and the number-average molecular weight as determined by gelpermeation chromatography. Quotients higher than approximately 5.0indicate polyester that is no longer essentially linear.

    ______________________________________                                        Mol % Pentanone Exposure (h)                                                                             Mz/Mn                                              ______________________________________                                        0.0%             0         3.59                                                               400        2.88                                               2.5%             0         3.37                                                               400        11.0                                               5.0%             0         3.30                                                               400        21.1                                               ______________________________________                                    

Example 9

Weathering Oriented Films of the Copolyesters

A copolyester of the same composition as described in Example 7(Inherent Viscosity=0.88) was extruded into film that was 500 micronsthick. This film was oriented (4×4) at 95° C., and the resulting clearfilm was approximately 40 microns thick. This oriented film was exposedto 400 hours of radiation in a xenon arc Weather-Ometer (AATCC-16-E).During this time period, the elongation was reduced by approximately 40%(84% to 53%) and the tensile strength was reduced by approximately 50%(223 MPa to 121 MPa). The elongation and tensile strength ofpoly(ethylene)terephthalate is basically unaffected by weathering underthese conditions as is the ketone-containing copolyester when placed inthe Weather-Ometer and shielded from the radiation.

Example 10 Copolymerization of1,5-bis-(4'methoxycarbonylphenyl)-3-pentanone, dimethyl terephthalateand ethylene glycol

Dimethyl terephthalate (72.8g),1,5-bis-(4'-methoxycarbonylphenyl)-3-pentanone (44.3g) ethylene glycol(52 g), manganese diacetate (55 ppm manganese), cobalt diacetate (80 ppmcobalt) and antimony trioxide (220 ppm antimony) were combined in aflask and stirred under N₂ at 200° C. for 1 h, 210° C. for 1.25 h and220° C. for 1 h. The temperature was raised to 270° C.-275° C. for 1.67h and the vacuum was quickly reduced to 0.10 mm of Hg. A light greenamorphous polymer resulted. The inherent viscosity was 0.74 asdetermined at 0.5 wt. % in a 60:40 solution of phenol/tetrachloroethane.Tg=66° C.; ¹ HNMR shows 28 mol % of ketone-containing monomer.

The invention has been described in detail with particular reference topreferred embodiments thereof, but it will be understood that variationsand modifications can be effected within the spirit and scope of theinvention. Moreover, all patents, patent applications (published orunpublished, foreign or domestic), literature references or otherpublications noted above are incorporated herein by reference for anydisclosure pertinent to the practice of this invention.

We claim:
 1. A polyester comprising repeating units having thestructure: ##STR10## wherein R¹ is selected from the group consisting ofhydrogen, alkyl having 1 to 6 carbon atoms and aryl having 6 to 10carbon atoms and R² is selected from the group consisting of hydrogen,alkyl having 1 to 6 carbon atoms, and aryl having 6 to 10 carbon atoms.2. The polyester of claim 1 wherein R¹ and R² are both hydrogen.
 3. Thepolyester of claim 1 wherein R¹ and R² are both methyl.
 4. The polyesterof claim 1 wherein R¹ to R² are both phenyl.
 5. The composition of claim1 wherein said polyester further comprises a repeating unit derived froma diol selected from the group consisting of ethylene glycol; propyleneglycol; 1,3-propanediol; 2,4-dimethyl-2-ethylhexane-1,3-diol;2,2-dimethyl-1,3-propanediol; 2-ethyl-2-butyl-1,3-propanediol;2-ethyl-2-isobutyl-1,3-propanediol; 1,3-butanediol; 1,4-butanediol;1,5-pentanediol; 1,6-hexanediol, 2,2,4-trimethyl-1,3-pentanediol;thiodiethanol; 1,2-cyclohexanedimethanol; 1,3-cyclohexanedimethanol;1,4-cyclohexanedimethanol; 2,2,4,4-tetramethyl-1,3-cyclobutanediol;p-xylylenediol; diethylene glycol; triethylene glycol; tetraethyleneglycol; and pentaethylene; hexaethylene; heptaethylene; octaethylene;nonaethylene; and decaethylene glycols or combinations thereof.
 6. Thepolyester of claim 1 further comprising a structural unit derived from adicarboxylic acid residue selected from the group consisting of oxalic;malonic; dimethylmalonic; succinic; glutaric; adipic; trimethyladipic;pimelic; 2,2-dimethylglutaric; azelaic; sebacic; fumaric; maleic;itaconic; 1,3-cyclopentane-dicarboxylic; 1,2-cyclohexanedicarboxylic;1,3-cyclohexanedicarboxylic; 1,4-cyclohexanedicarboxylic; phthalic;terephthalic; isophthalic; 2,5-norbornanedicarboxylic; 1,4-naphthalic;diphenic; 4,4'-oxydibenzoic; diglycolic; thiodipropionic;4,4'-sulfonyldibenzoic; 4,4'-biphenyldicarboxylic; and2,6-naphthalenedicarboxylic acids or esters thereof or combinationsthereof.
 7. The polyester of claim 1 wherein said repeating unit ispresent in the range of 0.1-100 mole % based on the total molepercentage of repeating units derived from diacids and diesters.
 8. Thepolyester of claim 7 wherein said repeating unit is present in the rangeof 0.1-15. mole % based on the total mole percentage of repeating unitsderived from diacids and diesters.
 9. The polyester of claim 8 whereinsaid repeating unit is present in the range of 1-5 mole % based on thetotal mole percentage of repeating units derived from diacids anddiesters.
 10. A polyester which is prepared from1,5-bis-(4'-methoxycarbonyl-phenyl)-3-pentanone, terephthalic acid orits esters, and a glycol component.
 11. The polyester of claim 10wherein the glycol component is ethylene glycol.
 12. An oriented filmprepared from the polyester of claim
 1. 13. A fiber prepared from thepolyester of claim
 1. 14. A molded object prepared from the polyester ofclaim 1.